An axial gap rotary electric machine is used for various applications for its characteristics such as thinning of a motor section, high inertia, and high efficiency, as a rotary electric machine used as a power source of an industrial machine. The axial gap rotary electric machine has a structure provided with a disc-shaped rotor having a relatively large diameter as compared with a general radial rotary electric machine. Thus, when a motor is configured in a determined diameter, the axial gap rotary electric machine has a characteristic that a larger torque can be obtained as compared with a radial motor since it is possible to make the diameter of the disc large. When a larger torque is expected, it is possible to configure an axial gap rotary electric machine having a structure provided with two rotors in an axial direction with respect to one stator. In such a system, many permanent magnets, which are magnetic field sources, can be arranged on the disc, and thus, it is possible to increase the amount of magnetic flux contributing to torque generation.
A method for obtaining high efficiency of an axial gap motor that includes one stator and two rotors is proposed in PTL 1. It is possible to suppress a loss to be generated by using an iron core, formed of an amorphous metal foil strip having a low loss, for an iron core section of the stator and using a material having a low loss such as an eddy current loss for a rotor magnet, and thus, it is possible to enhance the efficiency of the motor.
Meanwhile, it is also necessary to improve a heat dissipation property in order to obtain the high efficiency of the motor. A design of a heat dissipation path of heat generated in a stator of an axial gap motor that includes two rotors are studied in PTL 2 and PTL 3. In PTL 2, a conductive and high-thermal-conductivity member is provided between a stator core and a housing to provide a thermal heat dissipating channel to thermally conduct Joule heat generated by the stator to the housing. In addition, a system in which a fin spreading in a radial direction is arranged between adjacent cores, and a pipe thorough which a refrigerant flows is coupled to an end of the fin in an outer radial direction to cool the stator is studied in Patent Literature 3.